The perldoc program gives you access to all the documentation that comes with Perl. You can get more documentation, tutorials and community support online at http://www.perl.org/.
If you're new to Perl, you should start by running perldoc perlintro, which is a general intro for beginners and provides some background to help you navigate the rest of Perl's extensive documentation. Run perldoc perldoc to learn more things you can do with perldoc.
For ease of access, the Perl manual has been split up into several sections.
Full perl(1) documentation: perl
Perl officially stands for Practical Extraction and Report Language, except when it doesn't.
Perl was originally a language optimized for scanning arbitrary text files, extracting information from those text files, and printing reports based on that information. It quickly became a good language for many system management tasks. Over the years, Perl has grown into a general-purpose programming language. It's widely used for everything from quick "one-liners" to full-scale application development.
The language is intended to be practical (easy to use, efficient, complete) rather than beautiful (tiny, elegant, minimal).
Perl combines (in the author's opinion, anyway) some of the best features of C, sed, awk, and sh, so people familiar with those languages should have little difficulty with it. (Language historians will also note some vestiges of csh, Pascal, and even BASIC-PLUS.) Expression syntax corresponds closely to C expression syntax. Unlike most Unix utilities, Perl does not arbitrarily limit the size of your data--if you've got the memory, Perl can slurp in your whole file as a single string. Recursion is of unlimited depth. And the tables used by hashes (sometimes called "associative arrays") grow as necessary to prevent degraded performance. Perl can use sophisticated pattern matching techniques to scan large amounts of data quickly. Although optimized for scanning text, Perl also has many excellent tools for slicing and dicing binary data.
But wait, there's more...
Begun in 1993 (see perlhist), Perl version 5 is nearly a complete rewrite that provides the following additional benefits:
modularity and reusability using innumerable modules
Described in perlmod, perlmodlib, and perlmodinstall.
embeddable and extensible
Described in perlembed, perlxstut, perlxs, perlxstypemap, perlcall, perlguts, and xsubpp.
roll-your-own magic variables (including multiple simultaneous DBM implementations)
Described in perltie and AnyDBM_File.
subroutines can now be overridden, autoloaded, and prototyped
Described in perlsub.
arbitrarily nested data structures and anonymous functions
Described in perlreftut, perlref, perldsc, and perllol.
object-oriented programming
support for light-weight processes (threads)
Described in perlthrtut and threads.
support for Unicode, internationalization, and localization
Described in perluniintro, perllocale and Locale::Maketext.
lexical scoping
Described in perlsub.
regular expression enhancements
enhanced debugger and interactive Perl environment, with integrated editor support
Described in perldebtut, perldebug and perldebguts.
POSIX 1003.1 compliant library
Described in POSIX.
Okay, that's definitely enough hype.